The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Balance shafts are used for the inertia balance of reciprocating engines, in particular internal combustion engines; in machines with four cylinders, pairwise in line and with double the crankshaft speed. With other numbers and arrangements of cylinders, balance shafts are also used in different arrangements from case to case.
The demands on a balance shaft are substantially always the same irrespective of the type of construction of the engine: 1° A maximum of effect, that is eccentricity of the center of gravity, should be achieved with as little mass as possible; and 2° the bearing arrangement should be as precise as possible, which requires a minimum of deflection under the effect of centrifugal force. The latter must in particular be taken into account with large bearing spacings. The demand for a quietly running drive can be left out of consideration when it is only a question of the balance shaft per se.
A balance shaft is known from DE 198 07 180 A1 which extends over the total spacing between the bearings and whose cross-section is constant throughout and is a segment of a circle. The extent over the total length is a helpful measure when the bearing spacing is pre-set and cannot be reduced for various reasons. If, however, the development of the load due to the centrifugal force over the length is looked at with the eyes of a structural engineer, it can be recognized that the shape of the balance weight is not optimum.